Tweak bar colors used by "Total queries" graphic

[rdwebdesign]

What does this PR aim to accomplish?

Pi-hole v5 had only 2 categories to show: Blocked queries and Forwarded queries (allowed).

Now, Pi-hole v6 has 4 categories: Forwarded, Cached, Blocked and Other, but in some themes, the colors used for each category were very hard to distinguish between each other.

Example - Forwarded and cached were indistinguishable:

How does this PR accomplish the above?

Use more distinct colors and try to always use the same colors (Green for Forwarded, Red for Blocked, Blue for Cached - Other will use gray or any other color).

Link documentation PRs if any are needed to support this PR:

none

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